The invention is related to the stator coil of a generator used in such vehicles as automobiles, buses, trucks, and motorcycles.
Recently, the capacity of ac generators has become larger because of an increasing electric consumption in vehicles by an increasing number of electric and electronic equipment, used therein. At the same time, the generators are required to be even smaller to fit into the limited space provided for them. In order to provide such a high output small generator which meets the above requirements, it is necessary to improve the cooling characteristics of the generator, especially the cooling characteristics of the stator coil, because a substantial part of the heat generated during the operation of a generator is created by the stator coil.
In a conventional alternating current generator commonly used in vehicles, bundles of twined wire of the stator coil project from one or both sides of the stator core in the longitudinal direction. The projecting portion of the stator coil is cooled by cooling air generated by a fan that rotates with the rotor core. However, the problem in the conventional generator is that the smaller stator core wound in such a manner is not cooled effectively enough to permit a more compact and higher output generator.
In another conventional generator, the projecting portion of the stator coil is arranged so that the wires are spread approximately in a cylindrical form surrounding the rotor core in order to increase the surface of the projecting portion that may be exposed to the cooling air. However, this arrangement of the coil also fails to provide the above-mentioned cooling characteristics because the projecting portion of the stator coil interferes with the smooth and effective flow of cooling air. Therefore, this arrangement can worsen the cooling characteristics of the generator.
An object of the present invention, in view of the insufficient cooling characteristics of conventional generators, is to provide a generator used in vehicles having a stator coil with improved cooling characteristics, thereby, enabling both a more compact and more powerful generator.
Another object of the present invention is to provide a method for winding the wire of the stator coil around the stator core.